package com.sd.repay.utils;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Random;

public class CaptchaUtil {

    // 随机产生的字符串
    private static final String RANDOM_STRS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    private static final String FONT_NAME = "Fixedsys";

    private static final int FONT_SIZE = 18;

    private Random random = new Random();

    private int width = 80;// 图片宽

    private int height = 25;// 图片高

    private int lineNum = 50;// 干扰线数量

    private int strNum = 4;// 随机产生字符数量

    /**
     * 生成随机图片
     */

    public BufferedImage genRandomCodeImage(StringBuffer randomCode) {

        // BufferedImage类是具有缓冲区的Image类

        BufferedImage image = new BufferedImage(width, height,

                BufferedImage.TYPE_INT_BGR);

        // 获取Graphics对象,便于对图像进行各种绘制操作

        Graphics g = image.getGraphics();

        // 设置背景色

        g.setColor(getRandColor(200, 250));

        g.fillRect(0, 0, width, height);

        // 设置干扰线的颜色

        g.setColor(getRandColor(110, 120));

        // 绘制干扰线

        for (int i = 0; i <= lineNum; i++) {

            drowLine(g);

        }

        // 绘制随机字符

        g.setFont(new Font(FONT_NAME, Font.ROMAN_BASELINE, FONT_SIZE));

        for (int i = 1; i <= strNum; i++) {

            randomCode.append(drowString(g, i));

        }

        g.dispose();

        return image;

    }

    /**
     * 给定范围获得随机颜色
     */

    private Color getRandColor(int fc, int bc) {

        if (fc > 255)

            fc = 255;

        if (bc > 255)

            bc = 255;

        int r = fc + random.nextInt(bc - fc);

        int g = fc + random.nextInt(bc - fc);

        int b = fc + random.nextInt(bc - fc);

        return new Color(r, g, b);

    }

    /**
     * 绘制字符串
     */

    private String drowString(Graphics g, int i) {

        g.setColor(new Color(random.nextInt(101), random.nextInt(111), random

                .nextInt(121)));

        String rand = String.valueOf(getRandomString(random.nextInt(RANDOM_STRS

                .length())));

        g.translate(random.nextInt(3), random.nextInt(3));

        g.drawString(rand, 13 * i, 16);

        return rand;

    }

    /**
     * 绘制干扰线
     */

    private void drowLine(Graphics g) {

        int x = random.nextInt(width);

        int y = random.nextInt(height);

        int x0 = random.nextInt(16);

        int y0 = random.nextInt(16);

        g.drawLine(x, y, x + x0, y + y0);

    }

    /**
     * 获取随机的字符
     */

    private String getRandomString(int num) {

        return String.valueOf(RANDOM_STRS.charAt(num));

    }

    public static void main(String[] args) {

        CaptchaUtil tool = new CaptchaUtil();

        StringBuffer code = new StringBuffer();

        BufferedImage image = tool.genRandomCodeImage(code);

        System.out.println(">>> random code =: " + code);

        try {

            // 将内存中的图片通过流动形式输出到客户端

            ImageIO.write(image, "JPEG", new FileOutputStream(new File(

                    "random-code.jpg")));

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

}
